1. E. Simko WCVM Healing: First intention Second intention Prerequisites for healing: Debridement Tissue scaffold Germinal cells Blood supply Reference reading: Repair of the skin pp318-322, in Applied Veterinary Histology, W. J. Banks, 1993

2. Extreme temperatures (cold and burns) Solar injury (direct effect and photosensitization) Chemical/toxic injuries (ergot, fescue, Se) Self-inflicted injury Acral lick dermatitis (lick granuloma) Feline psychogenic alopecia Pyotraumatic dermatitis (hot spots) Injection site reactions Intertrigo (skin fold dermatitis) E. Simko WCVM

3. Allergy (Hypersensitivity) severe reaction to harmless foreign antigen E. Simko WCVM Autoimmune dz immune reaction against self-antigens Pathogenesis: tissue damage is mediated by four immune reactions: Type I, II, III, and IV

4. Immunologic diseases Allergen IgE Mast cell E. Simko WCVM

5. Immunologic diseases E. Simko WCVM IgG Cytotoxic effect Complement T cell

6. Immunologic diseases E. Simko WCVM Complement Immune complex deposition

7. Immunologic diseases Sensitized T cell Antigens Cytokines Chemotaxis and activation of macrophages E. Simko WCVM

8. Immunologic diseases Allergy (Hypersensitivity) severe reaction to harmless foreign antigen Mediated by type I and/or type IV reactions Common in dogs and horses, less common in cats and uncommon in food animals Erythema, pruritus, self-induced trauma E. Simko WCVM

9. Immunologic diseases - Allergic dz Inherited predisposition to type I reaction Average age of onset is from 1 to 3 years Respiratory route of allergen exposure (dogs) Lesions: erythema, urticaria, self-inflicted trauma (licking, rubbing) E. Simko WCVM

10. Immunologic diseases - Allergic dz There is no single confirmatory test Skin biopsy Rule out other allergies Intradermal allergy testing ELISA for allergen specific IgE Diagnosis E. Simko WCVM

11. Immunologic diseases - Allergic dz Most common allergic dermatitis in dogs and cats Type I and type IV reactions to flea saliva Seasonal pruritus with self-inflicted trauma (excoriation) and alopecia E. Simko WCVM

12. Immunologic diseases - Allergic dz Skin biopsy Demonstration of fleas Provocative exposure and response to therapy Diagnosis E. Simko WCVM

13. Immunologic diseases - Allergic dz Type I and/or type IV reactions Non-seasonal erythema, urticaria, alopecia, pruritus with self-inflicted trauma (licking, rubbing) E. Simko WCVM

14. Immunologic diseases - Allergic dz Skin biopsy Rule out other allergies Elimination diet trial (with absolute compliance) Diagnosis E. Simko WCVM

15. Immunologic diseases - Allergic dz Type IV reaction to chemicals (dyes, plant, soaps, detergents,…) Erythema, pruritus with self-inflicted trauma (exudation, crusts, alopecia) Diagnosis Skin biopsy Elimination trial E. Simko WCVM

16. Immunologic diseases Vesiculo-pustular dz often presented as persistent erosions and crusting Autoimmune dz immune reaction against self-antigens Mediated by type II or III reactions Variably pruritic, if not complicate by pyoderma E. Simko WCVM

17. Immunologic diseases - Autoimmune dz Group of vesicular/pustular diseases Pemphigus foliaceus (Ca, Fe, Eq, Cap) Acantholysis (anti-desmosomal antibodies) Bullous pemphigoid (Ca, Eq) (anti-hemidesmosomal antibodies) E. Simko WCVM

18. Immunologic diseases - Autoimmune dz Type III reaction Systemic lupus erythematosus Multiorgan disease Discoid lupus erythematosus Skin of the face Ab-Ag deposition E. Simko WCVM

19. Immunologic diseases - Autoimmune dz Autosomal dominant disease Puppies and young dogs Type III reaction - vasculitis E. Simko WCVM

20. Immunologic diseases - Autoimmune dz Clinical signs Histology Immunohistochemistry E. Simko WCVM